Extract text using regex in R

Question

I read the text file with below data and am trying to convert it to a dataframe

Id:   1
ASIN: 0827229534
  title: Patterns of Preaching: A Sermon Sampler
  group         


        

Answer 1

I am mostly using baseR here (apart from zoo and tiydr), may be little long code, but it can get the desired results.

options(stringsAsFactors = F)
text <- readLines("https://raw.githubusercontent.com/pranavn91/PhD/master/Expt/sample.txt") #Input file

textdf <- data.frame(text, stringsAsFactors = F) #Reading it
search_words <- c("Id","ASIN","title","group","salesrank","similar","avg rating") #search words as per OP
textdf <- data.frame(text = textdf[grepl(paste0(search_words,collapse = "|"), textdf$text),]) #finding the words and filtering it
textdf$key <- as.numeric(gsub("Id:\\s+(\\d+)","\\1",textdf$text))
View(textdf) # Making a key for each Id

textdf$key <- zoo::na.locf(textdf$key) #Propagating the key for same set of Ids
textdf$text <- gsub( "(.*)(?=avg rating:\\s*\\d+)","", textdf$text, perl=T) #Removing text from before "avg rating" 
textdf$text <- gsub("(similar:\\s*\\d+)(.*)","\\1", textdf$text, perl=T) #Removing text after "similar"
textdf$text <- trimws(textdf$text) ##removing leading and trailing blanks
textdf$text <- sub(":","+",textdf$text) #Replacing the first instance of : so that we can split with plus sign, since plus sign is very uncommon hence took it
splits <- strsplit(textdf$text, "\\+")  #Splitting 
max_len <- max(lengths(splits)) #checking for max length of items in the list
all_lyst_eq_len <- lapply(splits, `length<-`, max_len) #equaling the list
df_final <- data.frame(cbind(do.call('rbind', all_lyst_eq_len), textdf$key))# binding the data frame

df_final <- df_final[!duplicated(df_final),] #Removing the duplicates, there is some dups in data
df_f <- tidyr::spread(df_final, X1,X2) # Reshaping it(transposing)

df_f[,c("Id","ASIN", "title", "group","similar",
            "avg rating")] #Final dataset 

Output:

The text file is very wrapped up hence adding a screenshot , my apologies to community.

The output is ditto as per OP.